Conventional separation method for biological particles, particularly which is explained with cells, is as follows. Conventional cell separation methods comprising cell separation using the water-drop type cell suspension are divided into two kinds of ones. The first method is the separation method for cells by using a tube type cell separation apparatus using magnetic force and gravity, and the second one is the separation method using the size of minute tubes, which are the path for cell movement, and the size of cells to be separated.
First, the separation method for cells by using a injection-tube type cell separation apparatus using magnetic force and gravity accounts for 70 to 80 percent of cell separation method, presently performed worldwide. It functions by exercising magnetic field and injecting cell mixture liquid to the direction of gravity in the state that many iron balls of ferromagnetic material are included inside of the tube type cell separation apparatus. Where, as the positive cells to be separated from the cell mixture liquid are attached with magnetic bid by using an antigen-antibody reaction, the cells have a trait of being attached to surrounding magnetic material. If the cell mixture liquid is injected and magnetic filed is exercised, then the iron balls of ferromagnetic material become magnetic, and the specific cells magnetic bids are attached are attracted to the balls.
The method using the tube type cell separation apparatus using magnetic force and gravity uses iron balls with 50 to 100 [mu]m in diameter, as the size of air gap is different according to the size of iron balls, in order to separate positive cells with various size, there is a problem that the size of iron balls should be adjusted at every time. And, as the separation positive cells contact to iron balls directly, there is the possibility of cell loss and damage, and when the cells are injected in coagulation, as it is difficult for the cells to pass through air gap between iron balls, a process eliminating coagulated cells in advance by use of a sieve before separation is necessary.
Second, the separation method using the sizes of the minute tube for cell movement and positive cells to be separated is the one that specified cells move and are separated only through paths by forming the paths through which the mixture liquid is movable and by forming new path proper to specified cells in the end of the paths. According to the method, like the tube type cell separation apparatus using magnetic force and gravity, there is inconvenience to form new minute tube with new size and in case that smaller cells than the positive cell size are mixed, there is a difficulty of separating the positive cells all at once.
Finally, the cell separation method using suspension with form of water drop (Korean Patent Application No. 2004-25421), one of cell separation methods using magnetic force and gravity, is a method for separating only positive cells combined with magnetic bids by applying magnetic field at the state where a cell suspension with water-drop form is suspended down on the substrate. But, the method has problems that it needs a process of processing surface with hydrophilic and hydrophobic property and that the size and capacity of water drop are confined as it has a structure that water drops are hanged. And it has a defect that, as in order to form water drops, cell mixture liquid is injected directly into a water-drop type cell suspension formation part contacting a permanent magnet, and accordingly the method needs forming water drops and reversing the water-drop type cell suspension formation part, the water drops may be separated from the cell suspension formation part when rotating with the water-drop type cell suspension formation part.